U.S. patent application number 09/821876 was filed with the patent office on 2001-10-04 for silico-acrylic compositions: method for their preparation and use.
This patent application is currently assigned to Clariant ( France) S.A.. Invention is credited to Can Vu, Ngoc, Eranian, Armand, Vincent, Philippe, Wilhelm, Didier.
Application Number | 20010027223 09/821876 |
Document ID | / |
Family ID | 8848797 |
Filed Date | 2001-10-04 |
United States Patent
Application |
20010027223 |
Kind Code |
A1 |
Wilhelm, Didier ; et
al. |
October 4, 2001 |
Silico-acrylic compositions: method for their preparation and
use
Abstract
Fluid silico-acrylic compositions, stable in the long term,
polymerizable thermally and by radiatiion, by mechanism giving rise
to free radicals, with a very low water (less than 1%) and volatile
solvent content, containing silica, a silane, and a multifunctional
acrylic monomer, in which the silica is in the form of indivualized
particles with an average diameter with the range 9 amd 100 nm, not
interconnected by siloxane bonds, the silane is a vinyl silane with
the formula (I) H.sub.2C.dbd.CH--Si(OR).sub.3 (I) in which R
represents a methyl or ethyl radical, and the multifunctional
(meth)acrylic monomer is an alkoxylated (meth)acrylate, method for
preparation and use for the development of anti-scratch transparent
and uncoloured varnishes, obtained by polymerization giving rise to
free radicals by radiation (UV, electron bundles) or thermally.
Inventors: |
Wilhelm, Didier; (Issy les
Moulineaux, FR) ; Eranian, Armand; (Courbevoie,
FR) ; Can Vu, Ngoc; (Paris, FR) ; Vincent,
Philippe; (Compiegne, FR) |
Correspondence
Address: |
CLARIANT CORPORATION
Industrial Property Department
4331 Chesapeake Drive
Charlotte
NC
28216
US
|
Assignee: |
Clariant ( France) S.A.
|
Family ID: |
8848797 |
Appl. No.: |
09/821876 |
Filed: |
March 30, 2001 |
Current U.S.
Class: |
522/83 ; 522/172;
522/79; 522/84 |
Current CPC
Class: |
C08F 222/103 20200201;
C09D 4/06 20130101; C09D 4/00 20130101; C08F 230/085 20200201; C08F
290/142 20130101; C09D 4/06 20130101; C08F 290/142 20130101; C09D
4/00 20130101; C08F 230/085 20200201; C09D 4/00 20130101; C08F
222/103 20200201; C09D 4/00 20130101; C08F 222/102 20200201 |
Class at
Publication: |
522/83 ; 522/79;
522/84; 522/172 |
International
Class: |
C08K 003/36; C08G
077/20; C08F 002/48 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 3, 2000 |
FR |
00-04221 |
Claims
1. Fluid silico-acrylic compositions, stable in the long term,
polymerizable thermally and by radiation, by mechanism giving rise
to free radicals, with a very low water (below 1%) and volatile
solvent content, containing silica, a silane and a multifunctional
acrylic monomer, characterised by the fact that the silica is in
the form of individualised particles with an average diameter in
the range 9 to 100 nm, not interconnected by siloxane bonds, and
the silane is a vinyl silane of the formula (I) H.sub.2C.dbd.CH--Si
(OR).sub.3 (I) in which R represents a methyl or ethyl radical, and
the multifunctional (meth)acrylic monomer is an alkoxylated
(meth)acrylate.
2. Compositions according to claim 1, characterised in that they
contain 5 to 60 wt. % silica.
3. Compositions according to claim 2, characterised in that they
contain 30 to 50 wt. % silica.
4. Compositions according to claim 1, characterised in that they
contain silica in the form of individualised particles, not
interconnected by siloxane bonds, with an average diameter in the
range 12 to 50 nm.
5. Compositions according to claim 1, characterised by the fact
that the quantity of vinyl silane of formula (I) is within the
range 0.01 g to 1 g per gram initial dry silica.
6. Compositions according to claim 1, characterised by the fact
that the quantity of vinyl silane of formula (I) is within the
range 0.05 g to 0.7 g per gram initial dry silica.
7. Compositions according to claim 1, characterised by the fact
that the multifunctional (meth)acrylic monomer of the alkoxylated
(meth)acrylate type is of the ethoxylated or propoxylated
di(meth)acrylate type.
8. Compositions according to claim 1, characterised by the fact
that the multifunctional (meth)acrylic monomer of the alkoxylated
(meth)acrylate type is of the ethoxylated or propoxylated
tri(meth)acrylate type.
9. Compositions according to claim 8, characterised in that the
ethoxylated triacrylate monomer is the ethoxylated
trimethylolpropane triacrylate.
10. Compositions according to claim 8, characterised in that the
ethoxylated triacrylate monomer is the ethoxylated pentaerythritol
triacrylate.
11. Compositions according to claim 1, characterised by the fact
that the multifunctional (meth)acrylic monomer of the alkoxylated
(meth)acrylate type is of the ethoxylated or propoxylated tetra
(meth)acrylate.
12. Method for preparation of a composition as defined in claim 1,
characterised in that an aqueous silica sol containing the desired
quantity and grade of silica, the chosen quantity of vinyl silane
of formula (I), the desired quantity of multifunctional
(meth)acrylic monomer of the alkoxylated (meth)acrylate type, and
isopropyl alcohol are mixed at ambient temperature, under
agitation, then this mixture is subjected to distillation under
reduced pressure and under agitation, at a temperature below
50.degree. C. until the water and volatile solvents are
eliminated.
13. Method according to claim 12, characterised in that the initial
aqueous silica sol is an acid sol.
14. Method according to claim 13, characterised in that the initial
silica sol has a pH between 1 and 3.
15. Use of a composition as defined in claim 1 to develop
protective transparent and uncoloured coatings against abrasion,
obtained by polymerization giving rise to free radicals, by
radiation (UV, electron bundles) or thermally.
16. Use of a composition as defined in claim 1 to develop
anti-scratch, transparent and uncoloured varnishes, obtained by
polymerization giving rise to free radicals, by radiation (UV,
electron bundles) or thermally.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to fluid silico-acrylic
compositions, which are stable in the long term, polymerizable
thermally or by radiation, by a mechanism giving rise to free
radicals, and have a very low water and volatile solvents content,
their preparation method and application of these to obtain
abrasion and scratch-resistant coatings.
BACKGROUND OF THE INVENTION
[0002] Synthetic organic polymers and more particularly organic
polymers which are transparent to sunlight such as certain
(meth)acrylic or terephthalic resins are limited in their
development by their low resistance to abrasion and their tendency
to become scratched. To prevent these disadvantages, it is often
proposed to protect them by means of an anti-scratch and
anti-abrasion coating which can be obtained by photopolymerization
of a film of an aqueous or nonaqueous composition containing silica
particles and one or more polymerizable acrylic monomers, in the
presence of a photoinitiator and, possibly, one or more silanes. Of
these latter compositions, those described in the following patents
may be cited amongst others: U.S. Pat. Nos. 4,348,462, 4,455,205,
4,478,876, 4,486,504, 4,491,508, 4,822,828, 5,260,350,
5,374,483.
[0003] EP-A-317.858 describes the preparation of compositions in a
solvent medium containing a partial condensate of colloidal silica
with a silane, at least 60% of which is of the vinyl silane type, a
multi-functional (meth)-acrylate-type monomer, preferably
water-soluble, and a lower alkanol, preferably isopropanol. It is
this mixture in a solvent medium that is applied to synthetic films
to obtain abrasion-resistant coatings. These compositions contain
relatively large quantities of solvent that must be evaporated when
they are used.
[0004] U.S. Pat. No. 5,232,964 describes the preparation of a
composition which forms a transparent coating, which can be tinted
and is abrasion resistant following hardening by radiation,
comprising at least one multi-functional acrylate monomer, one
silane, colloidal silica dispersed in a solvent plus a quaternary
ammonium salt which makes it possible for the composition to be
tinted.
[0005] EP 926.170 describes fluid silico-acrylic compositions which
are transparent and uncoloured like water, stable in the long term,
polymerizable thermally and by radiation, by a mechanism giving
rise to free radicals, have a very low water content, below 1.5%,
and contain silica, a vinyl silane and tripropylene glycol
diacrylate.
[0006] Although the compositions described in these documents makes
it possible to obtain high-performance coatings, both with regard
to protection against abrasion and scratching, and with regard to
adhesion, research is still going on into compositions with even
better qualities, particularly as regards fluidity, stability over
time and protection of the environment (reduction in volatile
organic compounds or VOCs).
SUMMARY OF THE INVENTION
[0007] Now the applicant has discovered fluid compositions which
are stable in the long term, polymerizable thermally or by
radiation, by a mechanism giving rise to free radicals, with a high
concentration of silica, a very low water and volatile solvent
content, providing, after polymerization, a hard, adhesive coating
with good resistance to abrasion and scratching.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0008] The present invention therefore concerns fluid
silico-acrylics, which are stable in the long term, and are
polymerizable thermally or by radiation, by a mechanism giving rise
to free radicals, with a very low water and volatile solvents
content, containing silica, a silane and a multi-functional acrylic
monomer, characterised by the fact that silica is in the form of
individual particles having an average diameter between 9 and 100
nm, not connected to each other by siloxane bonds, and that the
silane is a vinyl silane with the formula (I)
H.sub.2C.dbd.CH--Si(OR).sub.3 (I)
[0009] in which R represents a methyl or ethyl radical, and the
multi-functional (meth)acrylic monomer is an alkoxylated
(meth)acrylate.
[0010] This water content is very low, less than 1%.
[0011] In the present invention's system the term "polymerizable
under radiation" indicates that the coating must be hardened under
ultraviolet radiation in the present of a photoinitiator or under
bundles of electrons without the need for a photoinitiator, and the
term "polymerizable thermally" indicates that the coating must be
hardened by heat treatment in the presence of a catalyst producing
free radicals.
[0012] In the alcoxylated (meth)acrylate, the alcoxyl preferably
contains no more than 10 carbon atoms, especially no more than 5
carbon atoms. The methoxy, ethoxy or proproxy radicals may be cited
for example.
[0013] The object of the invention is more particularly
compositions such as those defined above, characterised in that
they contain from 5 to 60 wt. % silica.
[0014] Among these latter compositions, the object of the invention
is especially compositions characterised in that they contain from
30 to 50% wt. % silica in the form of individual particles, not
connected to each other by siloxane bonds. Particles having an
average diameter within the range 12-50 nm are preferentially
retained.
[0015] Among the above compositions, those characterised by the
fact that they contain from 0.01 to 1 g may especially be cited,
preferably between 0.05 and 0.7 g of vinyl silane with the formula
(I) per gramme of initial dry silica.
[0016] Under preferential conditions, the above compositions are
characterised by the fact that the multi-functional (meth)acrylic
monomer of the alkoxylated (meth)acrylate type is of the
ethoxylated or propoxylated di(meth)acrylate type or by the fact
that the multi-functional (meth)acrylic monomer of the alkoxylated
(meth)acrylate type is of the ethoxylated or propoxylated
tri(meth)acrylate type. Especially preferred compositions are
characterised in that the ethoxylated triacrylate monomer is the
ethoxylated trimethylolpropane triacrylate, or characterised in
that the ethoxylated triacrylate monomer is the ethoxylated
pentaerythritol triacrylate.
[0017] Under other preferential conditions, the above compositions
are characterised by the fact that the multifunctional
(meth)acrylic monomer of the alkoxylated (meth)acrylate type is of
the ethoxylated or propoxylated tetra(meth)acrylate type.
[0018] The compositions according to the invention are stable in
the long term; in fact it is noted that, under optimum storage
conditions, i.e. in a cool, dark place, at the end of a period
ranging from several weeks to several months after preparation of
the product, there is still a clear, limpid, transparent solution.
There is no noticeable sedimentation of the silica, nor formation
of gels from the silica or the silanes. There is no appearance of
the phenomenon of turbidity.
[0019] The compositions according to the invention are especially
fluid. Their Brookfield viscosity after manufacture, determined at
20.degree. C. with a 100 tr/mn Brookfield RVT device is low (below
1500 mPa.s), which makes it possible to use them as they are
without subsequent dilution by solvents. This is especially
favourable with a view to reducing volatile organic compounds
(VOCs). They are also practically free of water and volatile
solvents. They mostly contain less than 1% water.
[0020] If it is desirable to reduce the viscosity of the
compositions according to the invention, solvents miscible with the
multifunctional (meth)acrylates can be used.
[0021] According to the invention, the compositions especially
preferred such as defined above can be prepared by a method
characterised in that a preferably acid aqueous silica sol
containing the desired quantity and grade of silica, the chosen
quantity of vinyl silane of formula (I), the desired quantity of
alkoxylated (meth)acrylate multifunctional monomer and isopropylic
alcohol, designated IPA, are mixed at ambient temperature, under
agitation, preferably in such a way that the quantity of vinyl
silane of formula (I), is within the range 0.01 to 1 g per gram of
initial dry silica, notably between 0.05 g and 0.7 g per gram of
initial dry silica, and this mixture is then subjected to
distillation under reduced pressure and under agitation, at a
temperature below 50.degree. C., until the water and volatile
solvents are eliminated to obtain a composition according to the
invention.
[0022] The silica particles, after elimination of the water and
volatile solvents lose their hydrophilic character and are thus
dispersed in the multifunctional alkoxylated (meth)acrylate
monomer.
[0023] The stability of the compositions according to the invention
is surprising and is particularly advantageous for their use.
[0024] In fact it is industrially very worthwhile to be able to
obtain compositions free of solvent which remain stable in the long
term.
[0025] The aqueous sol of acid silica is either available
commercially, or prepared extemporaneously by treatment according
to known techniques, with an ion-exchanging resin in acid form, of
a commercial aqueous solution of silica having a pH of 8 to 10.
[0026] Aqueous sols of silica are available commercially, notably
being marketed by the applicant under the name KLEBOSOL.RTM..
[0027] The initial aqueous sols of acid silica contain up to 60 wt.
% silica, in the form of individualised particles, with an average
diameter within the range 9 to 100 nm, not connected with each
other by siloxane bonds. They have a pH advantageously within the
range 1 to 3 and preferably approx. 2.
[0028] Under completely advantageous realisation conditions, the
silico-acrylic compositions according to the present invention
contain less than 2%, especially less than 1% and particularly no
quarternary ammonium salt.
[0029] The initial multifunctional alkoxylated (meth)acrylate
monomers used in the invention have good compatibility with water
as well as low toxicity which makes them advantageous in producing
compositions according to the invention. On the other hand, thanks
to their polyalkoxylated links, the multifunctional alkoxylated
(meth)acrylate monomers provide the compositions according to the
present invention with a good flexibility.
[0030] According to the invention, the vinyl silanes of formula (I)
and the multifunctional alkoxylated (meth)acrylate monomers are
commercial products.
[0031] The vinyltrimethoxysilane and the vinyltriethoxysilane are
marketed for example by the company Sivento under the tradenames
Dynasylan VTMO and Dynasylan VTEO respectively, and by the company
Witco under the tradenames Silquest A-171 and Silquest A-151
respectively.
[0032] The ethoxylated trimetholpropane triacrylate is notably
marketed by various companies: SR 454 marketed by Cray Valley,
Ebecryl 1100 marketed by UCB/Radcure.
[0033] The ethoxylated pentaerythritol triacrylate is notably
marketed by Servo Delden BV under the name RTT-193.
[0034] The compositions according to the invention have
advantageous properties because of their high silica concentration,
their fluidity and their stability over time. They can also be
easily deposited on different types of support previously
described, and hardened by a mechanism giving rise to free radicals
thermally or by radiation (UV or electron bundles) leading to the
formation of a thin film having good adhesion to the support and
good resistance to abrasion and/or scratches, which makes them
especially useful for the development of protective coatings or
uncoloured and transparent anti-scratch varnish.
[0035] This is why the object of the present invention is also a
method for protection of a synthetic organic polymer notably
against scratches and abrasion, characterised in that a layer of an
above composition is deposited on the said polymer, and the said
composition is then hardened.
[0036] The compositions according to the invention possessing
silica particles whose diameter is within the range 9 to 100 nm,
and particularly between 12 and 50 nm, are therefore especially
advantageous for obtaining anti-scratch varnishes on uncoloured and
transparent plastics, such as optical glasses or transparent
plastics materials which can be used in building and on other
substrates (non-transparent plastics, glass, wood, metal).
[0037] The following examples illustrate the present invention. In
these examples, the water dosages have been effected by the Karl
Fischer method and the silica rates have been determined by
calcination of a sample of known weight at 800.degree. C.
EXAMPLES
Example 1
[0038] The following are mixed under agitation in a reactor at
ambient temperature:
[0039] 122.4 g of an acid silica sol containing 40 wt. % silica,
i.e. 49 g silica with an average diameter of 50 nm, and 60% water,
i.e. 73.4 g water, and having a pH of 2.
[0040] 396.4 g isopropanol
[0041] 26 g vinyltrimethoxysilane, i.e. 0.53 g
vinyltrimethoxysilane per gram initial dry silica.
[0042] 125 g of ethoxylated trimethylolpropane triacrylate with a
molecular mass of 428.
[0043] The reactor is brought under reduced pressure of 50 to 110
mm of Hg and then gently heated in a double boiler so that the
temperature of the boiler does not exceed 45.degree. C. and that of
the reactional medium 35.degree. C. for 4 hours.
[0044] The water-isopropanol mixture is distilled so that the
quantity of residual water is below 1%.
[0045] After filtration, a slightly yellow, limpid, transparent
solution, stable in the long term, is obtained containing 30 wt. %
silica and 0.3% water and having a Brookfield viscosity of 304
mPa.s determined at 20.degree. C. (speed 100 tr/mn; mobile no.
2).
[0046] It is noted that under appropriate storage conditions, i.e.
in a cool, dark place, at the end of 6 months following the
preparation of the product, there is still a clear, limpid,
homogenous, transparent, slightly yellow solution, which is stable
in the long term, and no phenomenon of turbidity is therefore
found.
[0047] In the same way, the coatings obtained with this composition
have no film.
Example 2
[0048] The following are mixed under agitation in a reactor at
ambient temperature:
[0049] 192 g of an acid silica sol containing 30 wt. % silica, i.e.
57.6 g silica with an average diameter of 50 nm, and 70% water,
i.e. 134 g water and having a pH of 2.
[0050] 971 g isopropanol
[0051] 6 g vinyltrimethoxylsilane, i.e. 0.1 g vinyltrimethoxysilane
per gram of initial dry silica
[0052] 136.4 g ethoxylated trimethylolpropane triacrylate.
[0053] Under conditions analogous to those described in example 1,
after 6 hours of reaction at 35.degree. C., the water-isopropanol
mixture is distilled so that the quantity of residual water is
below 1%.
[0054] A clear, limpid, transparent, slightly yellow solution which
is stable in the long term is obtained, containing 29 wt. % silica
and 0.4 wt. % water, and having a Brookfield viscosity of 180 mPa.s
determined at 20.degree. C. (speed 100 tr/mn; mobile no.2).
[0055] It is noted that under appropriate storage conditions, i.e.
in a cool, dark place, at the end of 6 months after the preparation
of the product, there is still a clear, liquid, homogenous,
transparent, slightly yellow solution which is stable in the long
term. Thus no turbidity phenomenon is noted. In the same way, the
coatings obtained with this composition have no film.
Example 3
[0056] The following are mixed under agitation in a reactor at
ambient temperature:
[0057] 219 g of an acid silica sol containing 40 wt. % silica, i.e.
87.6 g silica with an average diameter of 12 nm and 60% water, i.e.
131.4 g water and having a pH of 2.
[0058] 945 g isopropanol
[0059] 6 g vinyltrimethoxylsilane, i.e. 0.07 g
vinyltrimethoxysilane per gram of initial dry silica
[0060] 206.4 g ethoxylated pentaerythritol triacrylate.
[0061] Under conditions analogous to those described in example 1,
the water-isopropanol mixture is distilled so that the quantity of
residual water is below 1%.
[0062] A clear, limpid, transparent, slightly yellow solution which
is stable in the long term is obtained, containing 29 wt. % silica
and 0.6 wt. % water, and having a Brookfield viscosity of 980 mPa.s
determined at 20.degree. C. (speed 100 tr/mn; mobile no.2).
[0063] It is noted that under appropriate storage conditions, i.e.
in a cool, dark place, at the end of 6 months after the preparation
of the product, there is still a clear, liquid, homogenous,
transparent, slightly yellow solution which is stable in the long
term. Thus no turbidity phenomenon is noted. In the same way, the
coatings obtained with this composition have no film.
Example 4
[0064] The following are mixed under agitation in a reactor at
ambient temperature:
[0065] 200 g of an acid silica sol containing 30 wt. % silica, i.e.
60 g silica with an average diameter of 12 nm and 70% water, i.e.
140 g water and having a pH of 2.
[0066] 1040 g isopropanol
[0067] 16 g vinyltrimethoxylsilane, i.e. 0.27 g
vinyltrimethoxysilane per gram of initial dry silica
[0068] 124 g ethoxylated pentaerythritol triacrylate.
[0069] Under conditions analogous to those described in example 1,
after 8 hours of reaction the water-isopropanol mixture is
distilled so that the quantity of residual water is below 1%.
[0070] A slightly yellow, limpid, transparent solution which is
stable in the long term is obtained, containing 32 wt. % silica and
0.6 wt. % water, and having a Brookfiield viscosity of 1470 mPa.s
(speed 100 tr/mn; mobile no.4).
[0071] It is noted that under appropriate storage conditions, i.e.
in a cool, dark place, at the end of 6 months after the preparation
of the product, there is still a clear, limpid, homogenous,
transparent, slightly yellow solution which is stable in the long
term. Thus no turbidity phenomenon is noted. In the same way, the
coatings obtained with this composition have no film.
Example 5
[0072] Example of use of formulations according to the invention
for production of coatings resistant to abrasion and scratches.
[0073] a) First of all, the following formulation is prepared by
mixing at ambient temperature (20.degree. C.):
[0074] 50 parts by weight of silica organosol of example 1
[0075] 50 parts by weight of the urethane-acrylate oligomer Ebecryl
5129 (UCB Radcure)
[0076] 5 parts by weight of photoinitiator IRGACURE 184 (Ciba
Specialist Chemicals).
[0077] b) The mixture thus obtained is deposited on a polycarbonate
support at a rate of approx. 50 g/m2. The polycarbonate support
thus coated is placed on a conveyor moving at a speed of 25
meters/minute under a tunnel equipped with a mercury vapour tube
with an average pressure of 120 W/cm (FUSION-SYSTEM) which emits
ultraviolet radiation to harden the coating.
[0078] c) The coating's resistance to abrasion thus hardened has
been evaluated by the Taber abrasion test with 2 CS 10 abrasive
grinding wheels and a 500 g weight applied to each of them,
followed by optical transmission measurement. The transmission
percentage is 100% when the formulation indicated is used, whereas
it is only 70% when a formulation containing no silica organosol
according to example 1 is used. Thus a very clear improvement in
the abrasion resistance of the coating containing the formulation
of example 1 is noted.
[0079] d) The scratch resistance was measured according to the
pencil hardness test. It is 7 H when the formulation indicated is
used, whereas it is only 4 H when the formulation contains no
silica organosol according to example 1. Thus a very clear
improvement in the scratch resistance of the coating containing the
formulation of example 1 is noted.
* * * * *